The OIG interviewed 54 witnesses who testified that some sensors at the Chula Vista
Station had been inhibited: 27 stated generally that sensors had been inhibited; 18
testified that sensors in the "valley" area had been inhibited at some point;
and 13 said they recalled that sensors in the "docks" area had been inhibited.
These witnesses included line agents, supervisory agents, station managers, Sector
Communications personnel, and Sector Electronics personnel. Like Imperial Beach, it was
clear that sensors had been inhibited but the question was when and why.

We received varying reports regarding when these sensors had been inhibited. Three
witnesses from Sector Communications testified that some unspecified sensors had been
inhibited for approximately three months during 1995, but they did not specify which three
months. One witness from Sector Electronics testified that the valley sensors had been
inhibited for three months in 1996. Various witnesses from Sector Communications and
Electronics testified that some Chula Vista sensors had been inhibited for one month in
1995, one month in 1996, and for two weeks in the spring of 1995. Accounts from agents at
Chula Vista were equally varied. One said he had requested that supervisors inhibit the
valley sensors shortly after Gatekeeper began because there was no manpower to work them;
thereafter, he stopped hearing these sensors being called out. Two witnesses
testified that the valley sensors had been inhibited in the spring of 1995. One said
the valley sensors had been inhibited for part of a shift one night in July 1995 after
they had been registering a lot of traffic. Two said the valley sensors had been inhibited
in the fall of 1995. One agent said the docks sensors had been inhibited in the fall
of 1995. Another agent testified that the valley sensors had been inhibited in May 1996.
One witness said the valley sensors had been inhibited for six months in the fall of 1995.
The person whom everyone identified as responsible for ordering the sensors inhibited, No.
1101, admitted having inhibited sensors on his shift throughout 1995, 1996, and 1997,
whenever he felt it was appropriate. He declared, however, that he had never inhibited the
docks sensors because his shift worked that area.

As with the Imperial Beach sensors, we found that we could not rely on recollections as
to timing. The three witnesses who testified that the valley sensors had been inhibited in
1996 were probably confused. Movement records indicated that at least one of these sensors
was removed in July 1995 and the rest were removed by mid-October 1995, leaving no sensors
in the valley area from October 1995 until September 1996 when new sensors were planted in
that area. It is unlikely that sensors would be planted in an area only to be inhibited
immediately thereafter. Given that the testimony of these witnesses is generally
consistent with that of others, save for the year, we believe they were simply mistaken on
this point.

In addition to the testimony of agents, we found documentary evidence that sensors were
in fact inhibited at Chula Vista. A memorandum to Sector Communications from No. 751, a
supervisor, requested that 11 sensors be inhibited from 3 p.m. to 7 a.m. from April 21,
1995, through May 10, 1995, at which time the policy was to be reviewed. Five of these
were the valley sensors, and five were relatively close to the border. We could not
determine the location of the eleventh. Interestingly, none of the witnesses from Sector
Communications said they recalled receiving this memorandum, and none mentioned No. 751 as
having requested that any sensors be inhibited. Each of them, however, recalled No. 1101
calling and requesting that various sensors be inhibited.

No. 751 testified that his memorandum was prompted by a line agent concerned that these
sensors were so close to agents' positions that agents were setting them off. For the five
listed sensors near the border this explanation makes sense. Indeed, No. 1101 offered the
same rationale for inhibiting them. This explanation could not have related to the five
valley sensors, however, because agents were not deployed anywhere nearby. According to
No. 1101, these sensors needed to be inhibited because livestock was frequently setting
them off and it made no sense to have agents respond to hits not caused by alien traffic.

No. 751 said he forwarded his memorandum to Sector Communications but did not recall
what occurred after that. We found no documentation of whether the continuous inhibition
of these 11 sensors on the swing and midnight shifts continued past May 11, 1995. No. 1101
testified, however, that he inhibited them on various shifts off and on, month after
month, depending on the weather, the level of manpower, and other constraints. Although he
could not recall specific dates, he said he had inhibited sensors before Gatekeeper and
continued to inhibit some sensors currently as he deemed appropriate.

It was harder to determine when the dock sensors were inhibited. Only five of the 13
witnesses who made this claim purported to have personal knowledge. One said late 1996,
but because he claimed the valley sensors - which in fact had been removed the previous
year - had been inhibited at the same time, his testimony was not reliable as to timing.
One witness said these sensors were inhibited sometime in the beginning of 1995. Another
claimed sometime in September 1995. The remaining two did not provide a time frame, but
said they had been inhibited because there was insufficient manpower to work these
sensors. Two of the persons who had merely heard rumors said they had heard that line
agents had asked Dispatch not to call out the dock sensors because there was no one to
work them. Two witnesses mentioned a memorandum sent to Dispatch listing a number of
sensors to be inhibited. Based on the description of the note, however, we believe they
must be referring to the memorandum already described, which did not deal with the dock
sensors.

The sensor report for February 11 through March 12, 1996, reporting the events and
tickets for each of the Chula Vista sensors, indicates that none of the sensors listed in
the April 1995 memorandum was inhibited during the time covered by the report. But it also
indicates that five different sensors were inhibited at some point during the month. Four
of these sensors could not have been inhibited for long because the difference between the
number of events and the number of tickets is small.189
The 202 sensor, however, recorded 1,082 events and 520 tickets, suggesting that it
was inhibited regularly, probably on a timer. Due to the limited information in this
report, we could not determine the dates or times the events without tickets occurred. In
recent times, however, this sensor has been put on a timer from 8 a.m. to 4 p.m. each
weekday when its site has significant levels of legitimate traffic.

In our review of the year's worth of sensor data beginning in mid-1996, we selected
five random months (which included typically busy and slow months) and found that nine
sensors at Chula Vista had been inhibited during that time. The 201 sensor was on a timer
during the weekdays as described above. Five of the other sensors previously inhibited
registered events without tickets on only a single day. The remaining sensors registered
events without tickets on 2, 5, and 16 days, respectively. Although the data does not
record exactly how long each of these sensors was inhibited, it does indicate that the
time between the first event without a ticket on a given day and the last event without a
ticket on that same day was on average less than two hours and in no case more than six
hours. This suggests that either these sensors were not inhibited for an entire shift or
there was very little traffic. In either case, these periods are not significant.190

In sum, we believe, based on the testimony of No. 1101 and others, that the valley
sensors were inhibited for extended periods throughout 1995 until they were removed in
July and October 1995. The five sensors located close to the border that were listed in
No. 751's memorandum also were inhibited frequently and for lengthy periods of time during
1995 and perhaps in early 1996. The dock sensors were inhibited on various occasions, but
we could not identify by whom or how often. Witnesses indicated, however, that these
sensors were inhibited when agents were not working that area. Other sensors appear to
have been inhibited on a sporadic basis. Significantly, by early 1996, the one sensor
report we obtained indicated that sensors were not being inhibited regularly or for
significant periods of time. This is particularly important because alien traffic is
generally high in February and March.

The next question is why these sensors were inhibited. Two agents alleged that the
sensors were inhibited to demonstrate that traffic had decreased. However, they offered
nothing to support this claim. Given that, as we have already noted, inhibited sensors
still register hits, and sensor hits were not used to measure traffic levels, we find the
claim both unsubstantiated and highly implausible. Four agents believed that the sensors
were inhibited to avoid detecting aliens and to lower apprehensions. They, too, offered
nothing but their suspicions, based on their belief that management wanted lower
apprehensions at all costs. In previous sections of this report, we found no evidence to
support the assumption that management wanted to avoid apprehending illegal aliens, and we
found no such evidence in connection with sensors.

In the end, we found the explanations offered by No. 1101 and by No. 751 in his
memorandum to be credible. The memorandum said the sensors were being inhibited due to the
deployment of agents closer to the border under Gatekeeper. No. 1101 also explained his
actions by noting that agents were deployed closer to the border, leaving no one to work
sensors so far from the border, and that sensors were frequently set off by livestock.
Other witnesses, including several line agents, concurred that these sensors were just too
far from the border to be worked when agents were assigned to positions along the border.
And this was the testimony of Sector Communications personnel as well. Given that the
valley sensors were in fact two to three miles from the border, where manpower was
concentrated, this explanation rings true.

The claim that five sensors close to the border were periodically inhibited because
agents kept setting them off also is credible. These sensors were located in prime
locations where agents frequently would be working. And the need to rely on sensors in
these areas was reduced because the sites could be surveilled by scope operators who could
direct agents to alien traffic.

It is telling that No. 751's memorandum explicitly ordered that these sensors remain
uninhibited when it rained, a period when sensors exhibit their highest level of activity.
Under rain conditions, agents are unable to work close to the border fence. If No. 751's
goal was to hide alien traffic and to prevent agents from being aware of traffic entering
the country, he would have been particularly interested in inhibiting these sensors when
it rained. His decision to do exactly the opposite substantially undercuts any inference
of ill motive behind the inhibiting of sensors at Chula Vista and corroborates the stated
resource-related explanations.

c. Summary of findings regarding inhibited sensors

Sensors at Imperial Beach and Chula Vista were inhibited, primarily in the first year
of Gatekeeper. At Imperial Beach, several sensors in the third tier away from where the
agents were usually positioned were inhibited on various occasions until late 1995.
Sensors at Chula Vista located far from the border were inhibited for extensive periods
until they were removed in late 1995. Other sensors close to the border that were being
set off by agents also were inhibited on numerous occasions in 1995. There was little
evidence of continued inhibiting of these sensors in 1996.

The decisions to inhibit these sensors were made at the Field Operation Supervisor
(FOS) level or below, shift by shift. There was no evidence of Sector input. This supports
the claim that the decisions arose out of particular operational needs and were not a
management attempt to alter the appearance of Gatekeeper results. And, in each case, we
found the claim that sensors were inhibited to hide the existence of alien traffic to be
unfounded, and particularly implausible, given that the ICAD system continues to register
hits when sensors are inhibited. Furthermore, because sensor hits were neither used to
measure traffic levels nor were publicly reported, any effort to manipulate sensor hits
would have had no impact on the reported success of Gatekeeper. We also found no evidence
that sensors were inhibited to keep apprehension levels lower.

189 The 202 sensor had 374 events and 357 tickets; the 203
sensor had 406 events and 396 tickets; the 220 sensor had 156 events and 152 tickets;
and the 429 sensor had 79 events and 56 tickets.

190 Although only 9 sensors registered events without
tickets (indicating inhibition), 15 sensors registered events for which tickets were
originally created but subsequently deleted. Unfortunately, the data does not record when,
why, or by whom the tickets were deleted. One of these deletions, for example, involves
the 201 sensor at 5:35 p.m., a time when legitimate traffic may have been present but the
sensor was no longer on a timer. Another possible explanation for such deletions is that
Dispatch already knew that an agent was going to be in the vicinity, making it unnecessary
to call out an event. Because of the extremely limited number of these deletions, we have
no reason to believe there was any inappropriate motive behind them. This lack of an audit
trail in the system, however, could permit abuse of the system to go undetected and is a
weakness that should be remedied.